You can unlock areas in the game by reaching certain milestones and opening the presents at said milestones. Become the envy of your friends as you collect more areas than them.

You should provide an option to buy the levels, so that you can be superior to your friends without having to play the game.

“If you wind up with a boring, miserable life because you listened to your mom, your dad, your teacher, your priest, or some guy on TV telling you how to do your shit, then YOU DESERVE IT.”― Frank Zappa